A patient develops urinary retention after abdominal surgery without urinary obstruction. Which strategy would most effectively promote urination?

In the scenario of a patient experiencing urinary retention following abdominal surgery without an obstruction, the administration of a cholinesterase inhibitor would be the most effective strategy to promote urination. Cholinesterase inhibitors work by preventing the breakdown of acetylcholine, which increases its availability in the synaptic cleft. This enhanced presence of acetylcholine stimulates the parasympathetic nervous system, specifically acting on muscarinic receptors within the bladder.

The activation of these muscarinic receptors leads to bladder contraction and promotes urination. In a postoperative context, where urinary retention may occur due to diminished bladder contractility, enhancing acetylcholine action can effectively alleviate this condition and facilitate urination.

Other potential strategies, such as activating nicotinic receptors or blocking muscarinic receptors, would not promote urination and could instead lead to muscle relaxation or inhibition of bladder function. Inhibiting the release of acetylcholine would also diminish the signals needed for bladder contraction, counteracting the goal of promoting urination. Therefore, the rationale behind choosing a cholinesterase inhibitor is grounded in its ability to augment acetylcholine's effects, leading to improved bladder function and relief of urinary retention.